Background

While many aspects of colonoscopic surveillance program for colorectal cancer (CRC) in patients with ulcerative colitis (UC) have evolved, it is unknown how the risk of CRC changed over time. We report data from one of the largest and longest-running UC surveillance programs in the world, revealing an important recent trend in CRC risk.

Methods

A retrospective review of histologically confirmed extensive UC patients enrolled in long-term surveillance was performed. The primary end point was defined as death, colectomy, withdrawal from surveillance, or the census date (January 1, 2013). We compared per-decade CRC incidence rate over the last forty years. Cancer detected in symptom-driven investigations or surgery prior to the next scheduled surveillance was defined as interval CRC.

Results

A total of 1,375 patients underwent 8,650 colonoscopies (median, 5 per patient; interquartile range (IQR), 3 - 8 per patient) during 15,234 patient-years of follow-up (median, 11 years; IQR, 7 - 17 years). Cancer was detected in 72 patients (5% of study population), of which 15 were interval CRC (20.8%). While the overall CRC incidence rate had decreased over the first three decades, there was a non-significant increase in the fourth decade (4.9 per 1,000 patient-years (PY)) compared with the third decade (3.7 per 1,000 PY; Chi-squared, P=0.30), which was attributable to a significant increase in Dukes' A or B cancer incidence rate in the fourth decade (3.2 per 1,000 PY) compared with the third decade (1.3 per 1,000 PY; P=0.045; figure 1). Likewise, there was an increase in incidence rate of UC-associated dysplasia (17.7 versus 11.7 per 1,000 PY; P=0.01). The incidence rate of Dukes' C or disseminated cancer showed a linear decreasing trend over the last four decade (2.5 to 1.4 per 1,000 PY in the first decade to last decade; Pearson's correlation, -0.99; P=0.01; figure 1).

“Figure 1: Per-decade incidence rate of CRC by Dukes’ stage”

Furthermore, despite the decrease in colectomy rate for dysplasia (linear regression, R= -0.43; P=0.007), incidence rate of interval CRC showed significant reduction over time (2.5 to 0.4 per 1,000 PY in the first decade to last decade; Pearson’s correlation, -0.99; P=0.007; figure 2).

“Figure 2: Per-decade incidence rate of interval CRC”

Conclusion

The colonoscopic surveillance is increasingly becoming effective in detection of cancer at an earlier stage and for reducing the interval cancer risk.